An MTA police K-9 unit patrols the Metro-North Railroad station in White Plains. Security has been heightened at many stations across the region in the wake of the attacks at the Boston Marathon. (April 16, 2013) Photo Credit: Xavier Mascarenas

"We are giving special attention to all train stations for the morning and evening rush hours," Yonkers Det. Lt. Patrick McCormack said.

Yonkers police have also been instructed to pay extra attention to potential targets within their patrol areas, including the Hillview Reservoir and shopping malls like Ridge Hill and Cross County.

In a news conference, Rick Deslauriers, FBI special agent in charge of the Boston division, vowed to pursue the Boston Marathon bombing investigation "to the ends of the earth," saying the investigation would be "worldwide."

Among the injured, 17 were critical, said officials, who declined to comment on a raid on a Revere, Mass., apartment and reports that suspects are in custody.

State Police Capt. Michael Jankowiak of Troop K, which patrols Westchester, Putnam, Dutchess and Columbia counties, said extra troopers were put on patrol Tuesday in response to the Boston attack.

"We have deployed overt and covert units at transportation hubs and critical infrastructure locations," he said. Jankowiak declined to discuss particular areas but in the past, potential targets like Metro-North stations, the Indian Point nuclear power plants and the Kensico Dam have received extra police attention in the wake of terror threats or attacks.

At Grand Central Terminal, a heavier-than-usual police and National Guard presence was reported by commuters.

"Basically, everyone in law enforcement is on a heightened alert," Jankowiak said. "But we've been fighting terrorist threats and attacks for more than a decade now and we know how to respond."

Commuter Miguel Hernandez, 25, of Dobbs Ferry, discounted the likelihood of a bombing in New York, though he acknowledged that there's always an outside chance.

"I'm not really worried," the city office worker said. "It's tragic, but I feel like it was an isolated incident. I'm not really worried that it's going to happen here. But it's New York, so anything can happen here."

At the White Plains Metro-North station, MTA police posted notices that backpacks and containers are subject to inspection. MTA police also issued a statement saying patrols on Metro-North trains would be beefed up.

Jankowiak said what set the Boston attack apart was the lack of any warning.

"There was no chatter. That's what's unusual," he said. "But from what we're being told, there will be information forthcoming today that will answer a lot of questions about this attack."

As always, he said, the public's help is a necessary part of thwarting attacks.

"It's become a cliche almost, but it's still very true: 'If you see something, say something.'"

All leads that State Police or other law enforcement agencies gather are reported to the New York State Intelligence Center, a central clearinghouse of intelligence databases. Those leads are then farmed out to relevant agencies, he said.

"We take information and tips on a daily basis," Jankowiak said. "When something like the Boston attack happens, those tips from the public are that much more important."

Westchester County Executive Rob Astorino ordered county police to deploy a helicopter to monitor critical infrastructure and boats to patrol the Hudson River. Bomb-sniffing dogs swept county buildings, including the county courthouse. And security was stepped up at Kensico Dam, Westchester County Airport and other locations.

Clarkstown police spokeswoman Sgt. Jo Anne Fratianni said the department is "on a heightened level of alert" and is touch with the management at Palisades Center, a popular shopping mall.

"We have a high level of concern about what happened in Boston," NYPD spokesman Paul Browne said.

Within minutes of the Boston explosions, NYPD officials and Mayor Michael Bloomberg ordered security ramped up at hotels, transportation hubs like Penn Station, the Grand Central and 42nd Street subway stations and Grand Central Terminal as well as popular tourist destinations such as Times Square, Radio City Music Hall and the World Trade Center site, Browne said.

The city has about 1,000 members of the NYPD assigned to counterterrorism duties.

Gov. Andrew M. Cuomo issued a statement saying he had directed the State Police, the Metropolitan Transportation Authority, the Port Authority of New York and New Jersey and other agencies to go on a heightened state of alert.

At the White Plains Metro-North station, Brewster resident Tony Bruce, who saw the second plane hit the World Trade Center as he headed to work on 9/11, was philosophical about security efforts to deter an attack.

"It could be any day at any time," he said. "The presence is a good deterrent, but nothing's foolproof."

The 53-year-old said a sense of false security has taken hold since 2001, but there's a limit to how far law enforcement can go.

"How do you patrol human behavior?" Bruce asked. "It's the world we live in, unfortunately."

At the Dobbs Ferry Metro-North station, Gina Mastrogiacomo, a 24-year-old Manhattan office worker, said she was less worried Tuesday morning than when she boarded her train home Monday night.

"I think yesterday I was more scared being at Grand Central Terminal," the Dobbs Ferry resident said. "I thought if something was going to happen, it would happen there. But today I'm not really worried."